In the early forties the Caproni planned the development of a new model of transport aircraft intended, as in the company's policy, to meet a possible increase in demand for travel on commercial airlines but that could be quickly converted for military purposes.

Gianni Caproni entrusted the project to the Director of the Technical Office of the establishments Taliedo, the engineer Alessandro Marchetti, who decided to change the previous SM75, always the result of his drawing board, re-proposing the general approach, three-engined monoplane wing low and fixed landing gear, introducing a stretched fuselage to accommodate, in civilian, 30 seats for passengers. This variant, which took over the company designation SM90, as a result of the higher maximum takeoff weight needed more power available than its predecessor that Marchetti found in the Alfa Romeo 135 RC.32 "Tornado", a radial aircraft engine recently started mass production and capable of delivering 1,400 hp (1,030 kW).

The prototype was built and flown from Taliedo during 1941, however, the demands of war due to the participation of the Kingdom of Italy in the Second World War persuaded Caproni to postpone the start of production of the new model, given the stalemate in civil aviation market, to focus sull'evasione the orders of the military models required by the Royal Air Force.

The S. M.90 was then stored in the hangars of Taliedo company until 1943 when, for the consequences of the signing of the armistice of Cassibile, the Wehrmacht, the German authorities decided to seize the specimen to be left to the testers of the Luftwaffe for the comparative flight tests. The performance explained by the model, however, failed to meet the German military authorities that they preferred the newer models and more technologically advanced. The only example so presumably taken charge of the Luftwaffe, it remained in Germany, where  the track was lost

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